The top surface of the National Stadium building is saddle-shaped, with a long axis of 332.3 meters and a short axis of 296.4 meters. The highest point is 68.5 meters high and the lowest point is 42.8 meters high. While maintaining the architectural style of the "Bird's Nest" unchanged, the new design plan has made significant adjustments and optimizations to the structural layout, construction section form, material utilization and other issues. The openable roof in the original design was cancelled, the roof opening was expanded, and the amount of steel used was greatly reduced through the optimization of the steel structure. The long-span roof is supported on 24 truss columns with a column spacing of 37.96 meters. The main trusses are arranged radially around the opening in the middle of the roof, and there are 22 main trusses that are directly connected or nearly connected. In order to avoid overly complex nodes, a small number of main trusses are cut off near the inner ring. The steel structure uses a large number of box-shaped components welded by steel plates. The cross-arranged main trusses and the secondary structures of the roof and facade form a special architectural shape of "Bird's Nest". The main stand adopts a reinforced concrete frame-shear wall structural system, which is completely separated from the long-span steel structure.

The "Bird's Nest" is the main stadium for the 2008 Beijing Olympic Games. The giant stadium design, completed by the 2001 Pritzker Prize winners Herzog and de Meuron in collaboration with Chinese architects, is shaped like a "nest" that breeds life. It is more like a cradle.

It expresses mankind’s hope for the future. The designers did not do anything superfluous to the national stadium, but simply left the structure exposed, thus naturally forming the appearance of the building.

The "Bird's Nest" is surrounded by a huge steel mesh and covers the stadium with 91,000 people; the sightseeing stairs naturally become an extension of the structure; the columns disappear, and the evenly stressed mesh is like tree branches without clear lines. The direction makes people feel that every seat is equal, and being in it is like returning to the forest; the inflatable membrane filters the sunlight into a diffuse shape, so that the stadium bids farewell to the shadow of the sun; the entire terrain is raised by 4 meters, and ancillary facilities are built inside to avoid The huge investment in digging earthwork was eliminated.

The Bird's Nest is a long-span curved structure with a large number of curved box-shaped structures. The design and installation are very challenging, and technological support is indispensable during the construction process. The "Bird's Nest" adopts today's advanced construction technology. The entire project has twenty or thirty technical problems. Among them, the steel structure is unique in the world. The "Bird's Nest" steel structure has a total weight of 42,000 tons, a maximum span of 343 meters, and the structure is quite complex. Its three-dimensional distortion is like twist processing. Problems such as settlement, deformation, and hoisting after construction are being gradually solved. Related construction technical problems are still Listed as a key research project of the Ministry of Science and Technology.

Now, the concrete construction of the "Bird's Nest" has been completed and the steel structure construction has begun. In order to effectively control the maximum wall thickness of the component, reduce the welding workload, and make the connection structure more reasonable, high-strength Q460 steel was used in the design at the location where the inner column of the truss column receives the greatest stress.

Speaking of Q460 steel, most people may not understand it. The "Bird's Nest" structural design is unique and novel, and the Q460 steel structure used to build it this time also has many unique features: Q460 is a low-alloy high-strength steel that will only undergo plastic deformation when its stress strength reaches 460 MPa. This strength is greater than that of ordinary steel, so it is very difficult to produce. This is the first time that Q460 steel has been used in a building structure in China; the thickness of the steel plate used this time is 110 mm, which is unique before. According to the national standard, the maximum thickness of Q460 is only 100 mm. In the past, this kind of steel was generally imported from Luxembourg, South Korea, and Japan. In order to provide a "fitting" Q460 for the "Bird's Nest", researchers from Henan Wuyang Special Steel Plant began scientific and technological research for more than half a year starting in September 2004, and finally succeeded in three trial productions. Today, the Q460 steel prepared for the "Bird's Nest" has begun mass production. In 2008, 400 tons of domestically produced Q460 steel with independent innovation and intellectual property rights will support the iron and steel bars of the "Bird's Nest".

——Little birds building nests

From the eastern Congo to the tropical savannas of South Africa, a weaver bird called the chaffinch can often be seen.

They make nests made of grass and many fibers of different flexibility, hanging from the branches like strange fruits. The weaver bird selects strong animal hair, most commonly from zebra or antelope, and secures its nest to a branch, using its beak to tie the hair into knots that always form a pattern as a mark. Such a bird's nest can bear the full weight of a pair of adult birds and several young birds living inside, and will not fall off despite wind and rain.

At the beginning of this century, natural science enthusiast Feren Marais discovered that young birds did not imitate their older companions when building nests. In order to eliminate the possibility of young birds being trained, Eren took a few eggs from the weaver's nest and secretly placed them in the nest of the canary he raised to hatch. When the chicks hatch out of their shells and grow up, they are moved to another specific place, where they are allowed to form "partners" and have children, while denying them any suitable habitat for nesting. materials, but let them lay their eggs directly on the bottom of the cage. The laid eggs were taken away and allowed to hatch by the canary... Through repeated experiments, the fourth generation of weaver birds not only severed their connection with their predecessors and the natural world, but also became completely domesticated artificially.

Now, he put a handful of grass, some twigs and fibers into the birdcage. The weaver bird goes to work using these materials in its cage. Soon the birds were weaving nests that hung in cages in the same style as those built by free-living previous generations. They are familiar with construction technology, and their knowledge in this area is no less than that of their great-grandfathers and great-grandfathers. They also know how to use fluffy but not strong horse hair to pad the bottom of the cage and never weave it onto the nest walls. If there is any leftover material, they will use it to strengthen the connection between the nest and the tree strips on the cage, and use it to tie it into a special knot with a "trademark".